Single Word Requests – Word for a Person Who Uploaded a File

Byronic hero or just Byronic seems close to what you want, but not exactly. A byronic hero is a moody, mysterious, aloof hero, but is also bitter, cynical, defiant, and self-absorbed (here).

Noir hero might do. Frank Miller writes "The noir hero is a knight in blood caked armor. He's dirty and he does his best to deny the fact that he's a hero the whole time" (here). But you needn't stick to Miller's definition. A noir hero is just any hero associated with the noir genre, and the character you describe might fit that bill.

How about disciple?

disciple: one who accepts and assists in spreading the doctrines of another; a convinced adherent of a school or individual [Merriam-Webster]

disciple: person who is a pupil or an adherent of the doctrines of another; follower [Dictionary.com]

disciple: one who embraces and assists in spreading the teachings of another [The Free Dictionary]

disciple: a person who believes in the ideas and principles of someone famous and tries to live the way that person does or did [Cambridge]

disciple: a follower or student of a teacher, leader, or philosopher [Oxford]

I can easily imagine using disciple in a video game. I like it better than sidekick. :-)